Iodide uptake

One of the early events of the apoptotic process involves the translocation of phosphatidylserine on the surface of cell membranes annexin V binding and propidium iodide uptake reveals various cellular states. After treatment with organotin(IV) compounds the cells could be categorized into populations vital cells (annexin V /P ), early apoptotic cells (annexin V /P ), late apoptotic cells (annexin V /P ), and necrotic cells (annexin V /P" ). Cells are observed with a fluorescence microscope and it is possible to observe translocation of phosphatidylserine (PS) from the inner side of the plasma membrane to the outer one and to see a green stain for annexin V FLUOS bound to PS, and a red stain for propidium iodide. 

What is the basic mechanism of action of thiocyanate in inhibiting iodide uptake by the thyroid gland ... 

C) Thiocyanate competitively inhibits iodide uptake by the thyroid follicular cells. 

D) Thiocyanate inhibits iodide uptake by a noncompetitive mechanism. 

C. Thiocyanate and other monovalent anions, such as perchlorate, inhibit iodide uptake by acting as competitive inhibitors of iodide uptake by the thyroid follicular cells. This is the only relevant action of these anions in this situation. 

Check the integrity of the bacterial membrane by measuring the percentage of propidium iodide uptake, by adding propidium iodide to an aliquot of the peptide-treated bacteria and to controls at a final concentration of 10 (xg/mL. 

J. A. Rillema, D. L. Rowady, Characteristics of the prolactin stimulation of iodide uptake into mouse mammary gland explants, Proc. Soc. Expl. Biol. Med., 215 (1997), 366 369. 

In thyroid cells in culture, ceilcitriol reduces production of cAMP in response to thyr oid stimulating hormone by a nuclear- action on the synthesis of G-protein subunits. However, it also reduces the responsiveness to cAMP, emd attenuates cell growth and iodide uptake in response to thyroid stimulating hormone, with a rapid time course from direct action on protein kinase A (Berg andHaug, 1999). 

FIGURE 18.14 Iodide uptake, transport, metabolism, and salvage in thyroid follicular cells. (Adapted from Rokita, Adler, McTarrmey, Watson, 2010.)... 

Iodide Uptake and Gene Expression as Endpoints in Thyroid Cell Models... 

Waltz F, Pillette L, Ambroise Y (2010) Anon-radioactive iodide uptake assay for sodium iodide symporter function. Anal Biochem 396(1/91-95... 

Three- to four-day old northern bobwhite were used to evaluate the influence of ammonium perchlorate (AP) on thyroid function, as well as thyroidal hormone level systemic effects on the hypothalamic-pituitary-thyroid axis [46], The perchlorate ion competitively inhibits iodide uptake, thus with time AP has the potential to reduce... 

Uptake of Iodide. Dietary iodine reaches the circulation as iodide. Normally, its concentration in the blood is very low (0.2-0.4 ag/dL about 15-30 uM), but the thyroid actively transports the ion via a specific, membrane-bound protein termed the sodium-iodide symporter (NIS). The ratio of thyroid to plasma iodide concentration is usually between 20 and 50 and can far exceed 100 when the gland is stimulated. The NIS is inhibited by a number of ions such as thiocyanate and perchlorate (Figure 56-3). Thyrotropin (see below) stimulates the NIS, which is controlled by an autoregulatory mechanism. Thus, decreased stores of thyroid iodine enhance iodide uptake, and the administration of iodide can reverse this situation by decreasing NIS protein expression. 

The first measurable effect of TSH on thyroid hormone metabolism is increased secretion, which is detectable within minutes. AU phases of hormone synthesis and secretion are eventually stimulated iodide uptake and organification, endocytosis, and proteolysis of thyroglobulin. There also is increased vascularity of the gland and hypertrophy and hyperplasia of thyroid cells. 

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